To make sense of what just went down, one had to witness the sheer insanity of Jake's violent outburst. That punch was the peak of his power and skill—the best he could deliver at that moment. Sure, maybe he could hit harder, but not by much—and definitely not without pushing past his limits or using some of his trump cards.
From the continent, the moon's explosion seemed instantaneous to those who witnessed it. But before that, Jake clearly saw how the avatar was blasted into its own moon, building up a ridiculous amount of kinetic energy.
On impact, the shockwave formed a plasma blast, splintering the satellite down to its core. Cracks spread all the way to the moon's dense nucleus, which barely held together. Moments later, the rest started falling apart as the avatar faded away, annihilated in an instant.
